JP4704571B2 - Method for preparing colored pigments - Google Patents

Abstract

The present invention relates to a process for preparing surface-modified colored pigments. The process includes the steps of: preparing a reaction batch comprising a treating agent and a diazotizing agent; adding a colored pigment to the batch; and mixing the colored pigment and the batch under high shear conditions to form a reaction product comprising a surface-modified colored pigment. The treating agent has an organic group which comprises at least one diazotizable group. In a preferred embodiment the diazotizable group comprises a) at least one aromatic group or at least one C1-C20 alkyl group, and b) at least one ionic group, ionizable group, nonionic group, or a mixture thereof. The surface-modified colored pigments prepared by the process of the present invention have been found useful in aqueous or solvent based compositions and particularly in ink jet ink compositions.

Description

＊顔料に対する加えられたスルファニル酸の量の比（ｗｔ％）
＊＊膜ろ過及び遠心分離の後での、得られた硫黄含有率（ｗｔ％）
＊＊＊膜ろ過及び遠心分離の後での、得られた窒素含有率（ｗｔ％）
＊＊＊＊粒度分布は、処理の直後で膜ろ過及び遠心分離の前に、ｗｔ％又はｖｏｌ％に基づいて決定した。未処理のＳｕｎｆａｓｔＢｌｕｅ１５：４顔料の粒度は、０．７ｗｔ％のＴｗｅｅｎ８０分散剤（ウィスコンシン州ミルウォーキーのＡｌｄｒｉｃｈ Ｃｈｅｍｉｃａｌから入手可能）を伴う顔料の０．１ｗｔ％水性分散体で決定した。
【００４７】
表１に示すように、本発明の方法を使用して亜硝酸ナトリウムと共にスルファニル酸を加えることは、硫黄含有率の増加で示されるように、Ｃ_６Ｈ_４ＳＯ_３ ⁻Ｎａ^＋基を有する表面改質青色顔料の生成をもたらす。０．５μｍ未満の平均粒度及び１．０μｍ未満の最大粒度を達成する能力も、比較的均一で効率的な処理方法に関係する。更に、限外ろ過及び遠心分離の後の表面改質有色顔料の収率は、本発明の方法を使用することによってかなり改良されている。
【００４８】
本発明の方法によって調製した表面改質青色顔料は容易に水性媒体に分散させることができ、また良好な色の色彩及び色強度を示す。これに対して、未処理の顔料は水に分散させることが非常に困難であり、また短い時間放置するとかたまる、すなわち凝集する。
【００４９】
例２：表面改質有色顔料の調製
例１の方法を繰り返すことによって、表面改質フタロシアニンブルー顔料を調製した。但しここではそれぞれ、スルファニル酸の初めの添加（顔料の導入前）の量が３．１６ｇで、２度目の添加（顔料導入の後）の量が３．１６ｇであり、また亜硝酸ナトリウムの初めの添加（顔料の導入前）の量が１．２６ｇで、２度目の添加（顔料導入の後）の量が１．２６ｇであった。更に、有色顔料は、表面積が６０ｍ^２／ｇのフタロシアニンブルー（ピグメントブルー、Ｚｕｌｕ４９６０、色指数（ＣＩ）Ｎｏ．４７１６０、オハイオ州ビーチウッドのＥｎｇｅｌｈａｒｄから入手可能）を使用した。得られた生成物は、Ｃ_６Ｈ_４ＳＯ_３ ⁻Ｎａ^＋基を有する表面改質青色顔料であった。生成物は２０μｍのスクリーンでろ過し、そして例１で示すようにして限外ろ過を行った。表面改質青色顔料分散体に遠心分離を行って、粒度が０．３５μｍよりも大きい全ての顔料粒子を実質的に除去した。遠心分離の後の分散体の全体としての収率は、青色顔料に基づいて１３ｗｔ％であった。
【００５０】
表面改質有色顔料の粒度分布は表２に示すようなものである。
【表２】

＊＊＊＊粒度分布は、例１で示される条件を使用する処理の直後に決定した。
【００５１】
例１と同様に、本発明の方法によって調製した表面改質青色顔料は、水性媒体に容易に分散し、且つ良好な色彩及び色強度を示した。しかしながら、限外ろ過及び遠心分離といった後処理の後での表面改質有色顔料の収率を改良するためには、表面積が比較的大きい顔料を使用できること（例１で示すように）又は有色顔料に従来の粒度減少処理を行って、処理剤及びジアゾ化剤を含む反応バッチに導入する前若しくは導入している間に粒度を小さくできることが認識される。
【００５２】
例３：表面改質有色顔料の調製
例１の方法を繰り返すことによって、表面改質フタロシアニンブルー顔料を調製した。但しここではそれぞれ、スルファニル酸の初めの添加（顔料の導入前）の量が２．７１ｇで、２度目の添加（顔料導入の後）の量が２．７１ｇであり、また亜硝酸ナトリウムの初めの添加（顔料の導入前）の量が１．０８ｇで、２度目の添加（顔料導入の後）の量が１．０８ｇであった。得られた生成物は、Ｃ_６Ｈ_４ＳＯ_３ ⁻Ｎａ^＋基を有する表面改質青色顔料であった。生成物を２０μｍのスクリーンでろ過し、そして例１で示すようにして限外ろ過を行った。表面改質青色顔料分散体に遠心分離を行って、粒度が０．３５μｍよりも大きい全ての顔料粒子を実質的に除去した。遠心分離の後の分散体の全体としての収率は、青色顔料に基づいて４０ｗｔ％であった。
【００５３】
表面改質有色顔料の粒度分布は表３に示すようなものである。
【表３】

＊＊＊＊粒度分布は、例１で示される条件を使用する処理の直後に決定した。
【００５４】
例１と同様に、本発明の方法によって調製した表面改質青色顔料は、水性媒体に容易に分散し、且つ良好な色彩及び色強度を示した。しかしながら、限外ろ過及び遠心分離といった後処理の後での表面改質有色顔料の収率を改良するためには、処理剤及びジアゾ化剤の量を増加させること（第１又は第２の導入として、又は追加の段階的な導入として）が好ましいことが認識される。
【００５５】
例４：表面改質有色顔料の調製
例１の方法を繰り返すことによって、表面改質フタロシアニンブルー顔料を調製した。但しここでは、スルファニル酸の代わりに、ｐ−アミノ−安息香酸（ウィスコンシン州ミルウォーキーのＡｌｄｒｉｃｈ Ｃｈｅｍｉｃａｌから入手可能）を、処理剤として初めの添加で５．３４ｇ添加し、そして２度目の添加で５．３４ｇ添加した。得られた生成物は、Ｃ_６Ｈ_４ＣＯ_２ ⁻Ｎａ^＋基を有する表面改質青色顔料であった。生成物を２０μｍのスクリーンでろ過し、そして例１で示すようにして限外ろ過を行った。表面改質青色顔料分散体に遠心分離を行って、粒度が０．３５μｍよりも大きい全ての顔料粒子を実質的に除去した。遠心分離の後の分散体の全体としての収率は、青色顔料に基づいて２０ｗｔ％であった。
【００５６】
表面改質有色顔料の粒度分布は表４に示すようなものである。
【表４】

＊＊＊＊粒度分布は、例１で示される条件を使用する処理の直後に決定した。
【００５７】
例１と同様に、本発明の方法によって調製した表面改質青色顔料は、水性媒体に容易に分散し、且つ良好な色彩及び色強度を示した。しかしながら、限外ろ過及び遠心分離といった後処理の後での表面改質有色顔料の収率を改良するためには、表面積が比較的大きい顔料を使用できること又は有色顔料に従来の粒度減少処理を行って、処理剤及びジアゾ化剤を含む反応バッチに導入する前に粒度を小さくできることが認識される。更に、処理剤及びジアゾ化剤の量の増加（第１又は第２の添加として、又は追加の段階的な添加として）が好ましいことがある。
【００５８】
例５：表面改質有色顔料の調製
平均直径が２ｍｍの６５０ｇのセラミック磨砕媒体（米国イリノイ州グルニーのＣＢ Ｍｉｌｌから入手可能）及び２６０ｍｌの脱イオン水を、加熱覆いを具備した５００ｍｌ磨砕機（米国オハイオ州アクロンのＵｎｉｏｎ Ｐｒｏｃｅｓｓから入手可能）に加えた。磨砕機を６０℃まで加熱し、４４０ｒｐｍの速度で操作した。スルファニル酸（２．９０ｇ）（米国ウィスコンシン州ミルウォーキーのＡｌｄｒｉｃｈ Ｃｈｅｍｉｃａｌから入手可能）を磨砕機に加え、実質的に全てのスルファニル酸が溶解するまで、セラミック媒体で約３０分間にわたって磨砕した。その後、２０．０ｇの脱イオン水に溶解した１．１６ｇの亜硝酸ナトリウム（ウィスコンシン州ミルウォーキーのＡｌｄｒｉｃｈ Ｃｈｅｍｉｃａｌから入手可能）を含有するバッチを、磨砕機に加えた。亜硝酸ナトリウムバッチに加えた直後に、表面積が６０ｍ^２／ｇの３０ｇのマゼンダ１２２顔料（Ｓｕｎｆａｓｔ１２２、色素指数（ＣＩ）Ｎｏ．７３９１５、オハイオ州シンシナティのＳｕｎ Ｃｈｅｍｉｃａｌから入手可能）を、磨砕機に加えた。得られる混合物を約１時間にわたって混合させて、その後で２．２ｇの追加のスルファニル酸を加え、そして０．８７ｇの追加の亜硝酸ナトリウムを加えた。磨砕機速度を４４０ｒｐｍにして、約１時間にわたって６０℃で混合物を反応させ、その後で２．２ｇの追加のスルファニル酸、そして０．８７ｇの亜硝酸ナトリウムを加えた。混合物は、磨砕機速度を４４０ｒｐｍにして、約５時間にわたって６０℃で混合物を反応させた。得られた生成物は、Ｃ_６Ｈ_４ＳＯ_３ ⁻Ｎａ^＋基を有する表面改質マゼンダ顔料であった。生成物を２０μｍのスクリーンでろ過し、そして例１で示すようにして限外ろ過を行った。表面改質マゼンダ顔料分散体に遠心分離を行って、粒度が０．３５μｍよりも大きい全ての顔料粒子を実質的に除去した。遠心分離の後の分散体の全体としての収率は、マゼンダ顔料に基づいて３５ｗｔ％であった。
【００５９】
表面改質有色顔料の粒度分布は表５に示すようなものである。
【表５】

＊＊＊＊粒度分布は、例１で示される条件を使用する処理の直後に決定した。
【００６０】
例１と同様に、本発明の方法によって調製した表面改質マゼンダ顔料は、水性媒体に容易に分散し、且つ良好な色彩及び色強度を示した。しかしながら、限外ろ過及び遠心分離といった後処理の後での表面改質有色顔料の収率を改良するためには、表面積が比較的大きい顔料を使用できること（例１でのように）又は有色顔料に従来の粒度減少処理を行って、処理剤及びジアゾ化剤の反応バッチに導入する前に粒度を小さくできることが認識される。
【００６１】
比較例６：表面改質有色顔料の調製
平均直径が２ｍｍの６５０ｇのセラミック磨砕媒体（米国イリノイ州グルニーのＣＢ Ｍｉｌｌから入手可能）及び２６０ｍｌの脱イオン水を、加熱覆いを具備した５００ｍｌ磨砕機（米国オハイオ州アクロンのＵｎｉｏｎ Ｐｒｏｃｅｓｓから入手可能）に加えた。磨砕機を６０℃まで加熱し、４４０ｒｐｍの速度で操作した。初めに処理剤とジアゾ化剤のバッチを磨砕機に投入した例１と違って、表面積が１３０ｍ^２／ｇの３０ｇの銅フタロシアニンブルー（ピグメントブルー、Ｓｕｎｆａｓｔ１５：４、色素指数（ＣＩ）Ｎｏ．７４１６０、オハイオ州シンシナティのＳｕｎ Ｃｈｅｍｉｃａｌから入手可能）を磨砕機に加え、そして６．７６ｇのスルファニル酸を加えた。顔料／スルファニル酸混合物を、全てのスルファニル酸が実質的に溶解するまで約３０分間にわたって、セラミック媒体で磨砕した。その後、２０．０ｇの脱イオン水に溶解した２．７３ｇの亜硝酸ナトリウム（ウィスコンシン州ミルウォーキーのＡｌｄｒｉｃｈ Ｃｈｅｍｉｃａｌから入手可能）からなるバッチを磨砕機に加えた。得られた混合物は、約１時間にわたって反応させ、その後で６．７６ｇの追加のスルファニル酸を加え、そして２．７３ｇの追加の亜硝酸ナトリウムを加えた。例１と同様に、磨砕機速度を４４０ｒｐｍにして、約５時間にわたって６０℃で混合物を反応させたが、６．６７ｇの追加のスルファニル酸、そして２．７３ｇの亜硝酸ナトリウムを加えた。混合物は、更に一晩にわたって反応させた。得られた生成物は、Ｃ_６Ｈ_４ＳＯ_３ ⁻Ｎａ^＋基を有する表面改質青色顔料であった。生成物を２０μｍのスクリーンでろ過し、そして例１で示すようにして限外ろ過を行った。表面改質青色顔料分散体に遠心分離を行って、粒度が０．３５μｍよりも大きい全ての顔料粒子を実質的に除去した。遠心分離の後の分散体の全体としての収率は、青色顔料に基づいて３５ｗｔ％のみであった。これに対して、本発明の方法を利用した場合の収率は６０％である。
【００６２】
表面改質有色顔料の粒度分布は表６に示すようなものである。
【表６】

＊＊＊＊粒度分布は、例１で示される条件を使用する処理の直後に決定した。
【００６３】
例１と比較して、表面改質有色顔料の粒度分布を表６に示している。例１で示される本発明の方法と比較すると、例６で使用されている従来の方法は、比較的大きい粒度分布で示されるように（特に９５％）効率的ではなく、また後処理の後での表面改質有色顔料の収率が有意に比較的低い。
【００６４】
比較例７：表面改質有色顔料の調製
１００ｇの脱イオン水を、機械的撹拌機を備えたホットプレート上の６００ｍｌのガラスビーカーに加えた。水を６０℃まで加熱し、４５０ｒｐｍで撹拌した。スルファニル酸（２．１ｇ）（ウィスコンシン州ミルウォーキーのＡｌｄｒｉｃｈ Ｃｈｅｍｉｃａｌから入手可能）をビーカーに加えて、実質的に全てのスルファニル酸が溶解するまで約３０分間にわたって撹拌した。その後、１０．０ｇの脱イオン水に溶解した０．８３ｇの亜硝酸ナトリウム（ウィスコンシン州ミルウォーキーのＡｌｄｒｉｃｈ Ｃｈｅｍｉｃａｌから入手可能）からなるバッチをビーカーに加えた。亜硝酸ナトリウムバッチを加えた直後に、表面積が６０ｍ^２／ｇの５．０ｇのフタロシアニンブルー（ピグメントブルー、Ｚｕｌｕ４９６０、色素指数（ＣＩ）Ｎｏ．７４１６０、オハイオ州ビーチウッドのＥｎｇｅｌｈａｒｄ社から入手可能）をビーカーに加えた。得られた混合物は、４５０ｒｐｍの撹拌機速度において、約６時間にわたって６０℃で反応させた。得られた生成物は、Ｃ_６Ｈ_４ＳＯ_３ ⁻Ｎａ^＋基を有する表面改質青色顔料であった。生成物を２０μｍのスクリーンでろ過し、そして例１で示すようにして限外ろ過を行った。表面改質青色顔料分散体に遠心分離を行って、粒度が０．３５μｍよりも大きい全ての顔料粒子を実質的に除去した。遠心分離の後の分散体の全体としての収率は、青色顔料に基づいて１０ｗｔ％未満であった。
【００６５】
表面改質有色顔料の粒度分布は表７に示すようなものである。
【表７】

＊＊＊＊粒度分布は、例１で示される条件を使用する処理の直後に決定した。
【００６６】
表面改質有色顔料の粒度分布は表７に示すようなものである。例１で示される本発明の方法と比較すると、例７で使用されている従来の方法は、比較的大きい粒度分布で示されるように（特に９５％）効率的ではなく、また後処理の後での表面改質有色顔料の収率が有意に比較的低い。また表面改質有色顔料は、ペースト状の材料の実質的な層を作り、これは２０μｍのスクリーンから廃棄しなければならなかった。生成物は、水性媒体と組み合わせるのに適当ではなかった。
【００６７】
例８：表面改質有色顔料の分散体安定性試験
例１の表面改質有色顔料（遠心分離の後）を、限外ろ過によって固体含有率が４．１％になるまで濃縮した。１０ｍｌの濃縮分散体を２０ｍｌのガラス瓶に入れた。この瓶に蓋をして、炉（オハイオ州ウィラードのＶＷＲ Ｓｃｉｅｎｔｉｆｉｃ Ｐｒｏｄｕｃｔｓから入手可能）に配置し、７日間にわたって７０℃に加熱した。この炉による処理（エージング）の前（例８Ａ）及び後（例８Ｂ）の両方での表面改質有色顔料の粒度分布を表８に示す。表８に示すように、４．１％の濃度の本発明の方法によって作った表面改質青色顔料は、この炉による処理の後でさえも、高いレベルのコロイド安定性を示した。
【表８】

＊＊＊＊粒度分布は、限外ろ過及び遠心分離の後処理工程の後で決定した。
【００６８】
例９：インクの調製
例１の表面改質有色顔料（遠心分離の後）を蒸留水に加えて、顔料が８．５ｗｔ％の水性分散体を作った。分散体は、３ｗｔ％の表面改質Ｓｕｎｆａｓｔ１５：４青色顔料、７．５ｗｔ％のエチレングリコール、７．５ｗｔ％のグリセロール、及び４．０ｗｔ％のイソプロパノール、及び残部の蒸留水を含むインクジェットインクにした。
【００６９】
得られたインクを使用して、ＢＣＩ−２１カートリッジを具備するＣａｎｏｎＢｕｂｂｌｅｊｅｔ ４２００プリンターで、一連の標準の紙（Ｘｅｒｏｘ４０２４、Ｆｏｘ Ｂｏｎｄ、ＫＧ）及び１つの透明基材に青色の印刷を行った。３刺激値、水堅牢性（ＷＦ）、及び光学濃度（ＯＤ）の結果を表９に示す。比較のために、工場から供給されるＢＣＩ−２１カートリッジ青色染料で得られる結果も表９に示している。更なる比較のために、ＥＮＣＡＤ ＧＯ Ｇｒａｐｈｉｃ Ｏｕｔｄｏｏｒ Ｉｎｋに基づく顔料（米国カルフォルニア州サンディエゴのＥＮＣＡＤから入手可能）にも同じ試験を行って、結果を表９に示している。
【００７０】
Ｈｕｎｔｅｒ Ｌａｂ Ｓｃａｎ ＩＩ装置（米国バージニア州レストンのＨｕｎｔｅｒ Ａｓｓｏｃｉａｔｅｓ Ｌａｂｏｒａｔｏｒｙ社から入手可能）を使用して、色の３刺激値Ｌ^＊、ａ^＊及びｂ^＊を決定した。光学濃度（ＯＤ）は、Ｍａｃｂｅｔｈ濃度計ＲＤ９１５Ｓ（ニューヨーク州ニューウィンザーのＧｒｅｔａｇＭａｃＢｅｔｈ ＬＬＣから入手可能）を使用して、ＡＮＳＩ法ＣＧＡＴＳ，４−１９９３に従って決定した。水堅牢性（ＷＦ）は、初めに印刷物を約４５°の角度でぶら下げ、所定の期間（印刷後１分、印刷後５分等）で２５ｍｌの水を噴出し、そして色の移動を観察することによって決定した。ここで、噴霧した水が透明で流れた時点で、印刷が耐水性であると考える。
【００７１】
上述の商業的に入手可能な２つのインクと比較すると、表９の結果は、本発明の方法によって調製した表面改質青色顔料が、最適化されていないインクジェットインク組成物で、２つのタイプの紙において良好な印刷能力及び水堅牢性を示すことを表している。
【表９】

【００７２】
本発明の方法によって調製した表面改質有色顔料は、最適化されていない組成物中であっても、良好な印刷性能を示し、また商業的に入手可能な染料及び顔料の有色製品の代替として魅力的である。得られるインクジェットインクは、３刺激値及び水堅牢性によって示されるように、美観的に好ましい青色の印刷を提供する。
【００７３】
上述のように、本発明の方法によって調製された表面改質有色顔料は、水又は溶媒に基づく幅広い用途で有益であり、特に所望の色及び強度を提供するインク組成物で有益である。従来の顔料と違って、本発明による表面改質有色顔料は所望の液体ビヒクルに容易に分散させることができる。更に、本発明による表面改質有色顔料は液体ビヒクル中においてコロイドとして安定であり、従来の磨砕も分散剤の補助も必要ではない。本発明による表面改質有色顔料は、液体ビヒクルに分散させるために低剪断混合又は撹拌のみを必要とする。
【００７４】
上述の本発明の説明は説明のためだけのものであり、本発明を限定するものではない。従って当業者は、上述の技術を参照して又は本発明を実施して、変更又は変形を行うことができる。本発明の態様は本発明の原理を説明するために選択され記載されたものであり、従って当業者は、意図する特定の用途に適当なように、様々な変更を行って本発明の様々な態様を使用することができる。本発明の範囲は特許請求の範囲及びその均等物で定義されている。[0001]
[Background of the invention]
  The present invention relates to colored pigments and aqueous compositions comprising colored pigments, in particular surface modified colored pigments, and ink compositions useful for imaging applications such as inkjet inks.
[0002]
[Description of related technology]
  Manufacturers are increasingly required to replace traditional solvent-based systems with aqueous systems, so automotive parts coatings, industrial coatings, paints, paper, inks, toners, adhesives, latex Aqueous systems are being used in many applications such as. Such aqueous systems are known and generally contain colorants such as dyes. It is dissolved in an aqueous vehicle such as water or a mixture of water and a water soluble organic solvent or water miscible organic solvent.
[0003]
  While it is easy to utilize dye-based systems, dyes have some drawbacks when used in aqueous ink systems. For example, water-soluble dyes in a water / organic mixture will dissolve and flow when exposed to moisture or water. The dye image may become soiled or rubbed when in contact with a felt pen or when touched or rubbed with a finger. In addition, dyes have insufficient light stability when exposed to visible or ultraviolet light.
[0004]
  Pigments may also be used as colorants in aqueous compositions, but due to problems with composition performance and reliability, i.e., print quality, stability, latency, etc. The tolerance in aqueous systems is not great. Examples of such pigments include carbon black, titanium dioxide white, cobalt blue (CoO-Al₂O₃), Phthalocyanine blue, phthalocyanine green, and chrome yellow (PbCrO)₄).
[0005]
  Johnson et al., US Pat. No. 5,837,045, describes new surface-modified colored pigments and aqueous compositions containing such surface-modified colored pigments. Such surface-modified colored pigments are a significant improvement over dye-based systems or conventional pigment systems (ie pigments that require stabilization with polymers or surface-active compositions), but improved surface modification. Colored pigments and methods for their production, as well as water or solvent based compositions containing such surface-modified colored pigments, are still in particular for ink compositions that require long-term colloidal stability and light fastness. is needed. It is also desirable to produce an improved aqueous ink composition that exhibits improved latency and recoverability in each printing system while providing good printing performance. There is also a need for improved aqueous ink compositions with improved water resistance.
[0006]
[Summary of the Invention]
  The present invention relates to a method for preparing a surface-modified colored pigment. The method comprises preparing a reaction batch containing a treating agent and a diazotizing agent, adding a colored pigment to the reaction batch, and mixing the colored pigment and the reaction batch at high shear conditions to produce a surface modified colored pigment. Producing a reaction product comprising The treating agent here has at least one diazotizable groupTheIn a preferred embodiment,Processing agent(A) at least one aromatic group, at least one C₁~ C₂₀Having an alkyl group, or a mixture thereof, and (b) at least one ionic group, an ionizable group, a nonionic group, or a mixture thereof.
[0007]
  The present invention further relates to a method for preparing an ink composition incorporating the above-described surface-modified colored pigment.
[0008]
  Surface-modified colored pigments prepared by the method of the present invention can be used in water or solvent based compositions containing conventional pigments. Such compositions can include, for example, automotive coatings, industrial coatings, printing plates, paints, papers, toners, inks (particularly inkjet ink compositions), adhesives, latexes, fabrics, and fibers. Surface modified colored pigments can be adjusted to be compatible with specific water or solvent based systems, and are relatively simple and relatively complete dispersion, improved colloidal stability, and relatively strong color strength And can be adjusted to provide light and dark.
[0009]
[Detailed Description of the Invention]
  The present invention relates to a method for preparing a surface-modified colored pigment. The method comprises preparing a reaction batch containing a treating agent and a diazotizing agent, adding a colored pigment to the reaction batch, and mixing the colored pigment and the reaction batch at high shear conditions to produce a surface modified colored pigment. Producing a reaction product comprising
[0010]
  The treating agent used in the method of the present invention has at least one diazotizable group.TheFor the purposes of the present invention, a “diazotizable group” means a diazotizing agent.WhenReact to diazoniumBaseMake nitrogen containingBaseMeans. “Diazotizing agent” means a diazotizable groupTreatment agent havingDuring the reaction withA diazotizable groupGive a nitrogen atom,By any compound that makes a diazonium salt is meant. In a preferred embodiment,Processing agent(A) at least one aromatic group, at least one C₁~ C₂₀It has an alkyl group, or a mixture thereof, and (b) at least one ionic group, ionizable group, nonionic group, or a mixture thereof.
[0011]
  At least one aromaticGroupExamples include, but are not limited to, unsaturated cyclic hydrocarbons having one or more rings, which may be saturated or unsaturated, for example having an alkyl group. Examples of the aromatic group include an aryl group (for example, phenyl, naphthyl, anthracenyl and the like) and a heteroaryl group (for example, imidazolonyl, pyrazonyl, pyridinyl, thienyl, thiazolyl, furyl, triazinyl and indornyl). At least one C₁~ C₂₀AlkylGroup, It may be branched or unbranched, and may be substituted or unsubstituted. In a preferred embodiment, at least one aromatic group of the diazotizable group or at least one C₁~ C₂₀The alkyl group is directly bonded to the colored pigment.
[0012]
  Can be usedProcessing agentA preferred group of is an organic group substituted with an organic group substituted with an ionic group, an ionizable group or a nonionic group as a functional group. An ionizable group is a group capable of creating an ionic group in the medium used. The ionic group can be an anionic group or a cationic group and the ionizable group can create an anion or cation. Non-ionic groups are groups that have no charge or cannot have a charge. Alternatively, nonionic groups can include zwitterions (ie, ions having both positive and negative charges), thereby creating an overall neutral group.
[0013]
  Examples of the ionizable functional group that forms an anion or an anionic group include an acidic group or a salt of an acidic group. ThereforeProcessing agentIs a group derived from an organic acidCan have. PreferablyProcessing agentSuch that when it has an ionizable group that forms an anion, such asProcessing agent(A) an aromatic group or C₁~ C₂₀And (b) pK_aAt least one acidic group having a pK of less than 11, pK_aA salt of at least one acidic group having an A of less than 11, or pK_aAt least one acidic group with a pK of less than 11 and pK_aHaving a mixture with a salt of at least one acidic group of less than 11. PK of acidic group_aIsProcessing agentPK as a whole_aPK with only acidic substituents_aNot to mention. More preferably pK_aIs less than 10, most preferably pK_aIs less than 9. PreferablyProcessing agentThe aromatic group is directly bonded to the colored pigment. The aromatic group may or may not be further substituted, for example with an alkyl group. More preferably,Processing agentIs phenyl or naphthyl groupHaveThe acidic group is a sulfonic acid group, a sulfinic acid group, a phosphoric acid group or a carboxylic acid. More preferablyProcessing agentIs a substituted or unsubstituted sulfophenyl group or a salt thereof, a substituted or unsubstituted (polysulfo) phenyl group or a salt thereof, a substituted or unsubstituted sulfonaphthyl group or a salt thereof, or Substituted or unsubstituted (polysulfo) naphthyl groups or salts thereofHave.
[0014]
  Anionic natureTreatment agent groupExamples of include, but are not limited to, -C₆H₄-COO⁻X⁺, -C₆H₄-SO₃ ⁻X⁺, -C₆H₄-(PO₃)^-22X⁺, -C₆H₂-(COO⁻X⁺)₃, -C₆H₃-(COO⁻X⁺)₂,-(CH₂)_z-(COO⁻X⁺), -C₆H₄-(CH₂)_z-(COO⁻X⁺). Where X⁺Is Na⁺, H⁺, K⁺, NH₄ ⁺, Li⁺, Ca²⁺, Mg²⁺Z is an integer from 1-18. As those skilled in the art will recognize, X⁺Can be made in situ as part of a manufacturing process, or can be attached to an aromatic or alkyl group by a typical salt exchange or ion exchange process.
[0015]
  An amine is an example of an ionizable group that creates a cation or cationic group and can be attached to the group in the same manner as described above for the ionizable group that produces an anion. For example, amines can be protonated in acidic media to produce ammonium groups. Preferably with an amine substituentProcessing agentPK_aIs less than 5. Quaternary ammonium group (-NR₃ ⁻), The fourth phosphonium group (-PR₃ ⁻), And a sulfonium group (-SR₂ ⁻) Is also an example of a cationic group. PreferablyProcessing agentHas an aromatic group, such as a phenyl or naphthyl group, and a quaternary ammonium group or quaternary phosphonium group or sulfonium group. The quaternary amine and the quaternary aromatic amine are alsoIn treatment agentCan be used. In this connection, therefore, N-substituted pyridinium compounds such as N-methyl-pyridyl can also be used.
[0016]
  Has cationic propertiesTreatment agent groupExamples of, but are not limited to, -C₆H₄N (CH₃)₃ ⁺Y⁻, -C₆H₄COCH₂N (CH₃)₃ ⁺Y⁻, -C₆H₄(NC₅H₅)⁺Y⁻,-(C₅H₄N) C₂H₅ ⁺Y⁻, -C₆H₄COCH₂(NC₅H₅)⁺Y⁻,-(C₅H₄N) CH₃ ⁺Y⁻And -C₆H₄CH₂N (CH₃)₃ ⁺Y⁻Can be mentioned. Where Y⁻Is any halogen ion or anion, such as NO₃ ⁻, OH⁻, CH₃COO⁻Or a combination thereof. As those skilled in the art understand, Y⁻Can be made in situ as part of a manufacturing process, or can be attached to an aromatic or alkyl group by a typical salt exchange or ion exchange process.
[0017]
  Based on anions and cationsTreatment agent groupOther examples are US Pat. Nos. 5,571,311, 5,630,868, 5,707,432, and 5,803,959, and PCT International Publication. This is described in WO96 / 18688 and WO96 / 18690. The description of these specifications is referred to here, the entire description of which is included in the description of this specification.
[0018]
  Other examples of ionic or ionizable functional groups include amphiphilic counterions that may have cation or anion properties. Amphiphilic counterions are typically shown as molecules or compounds having a “head” with hydrophilic polarity and a “tail” with hydrophobic properties. Representative examples of cationic and anionic amphiphilic counterions include those described above and those described in Adams et al. US Pat. No. 5,698,016. The description of this patent specification is hereby incorporated by reference in its entirety.
[0019]
  With regard to the further description of the method of the present invention for preparing surface modified colored pigments, if zwitterionic counterions are desired, the surface modified colored pigments described above are cationic functional (ie positive charge) or anionic functional (ie negative). Charge). Preferably the charge bound to the pigmentProcessing agentC₁~ C₂₀Of alkyl groups or aromatic groups. If the desired surface-modified colored pigment property is anionic, the amphiphilic counterion is either cationic or has a positive charge. Similarly, if the surface-modified colored pigment is cationic in nature, the amphiphilic counterion is anionic or has a negative charge.
[0020]
  Examples of cationic amphiphilic counterions include, but are not limited to, the ammonium ions described above that can be made by adding acid to the following compounds: fatty amines, esters of amino alcohols, alkyls Amines, polymers with amine functional groups, polyethoxylated amines, polypropoxylated amines, polyethoxylated polypropoxylated amines, anilines and derivatives thereof, fatty alcohol esters of amino acids, polyamines N-alkylated with dialkyl succinates, heterocycles Amines derived from amines, fatty amines, guanidines derived from alkylamines, guanidines derived from arylamines, amidines derived from fatty amines, amidines derived from fatty acids, amidines derived from alkylamines, or ants Amidine derived from triethanolamine. PK of ammonium ion_aIs preferably a protonated aromatic group or alkyl group on the pigment pK_aBigger than.
[0021]
  Specific examples of cationic amphiphilic ions include dioctyl ammonium, oleyl ammonium, stearyl ammonium, dodecyl ammonium, dimethyl dodecyl ammonium, stearyl guanidinium, oleyl guanidinium, soy alkyl ammonium, coco alkyl ammonium, oleyl ammonium ethoxy. Mention may be made of rate, protonated diethanolamine dimyristate, and N-oleyldimethylammonium. Preferred cationic amphiphilic ions include ditallow alkyl ammonium, dimethyl oleyl ammonium, cocoalkyl dimethyl ammonium, and dimethyl hydrogenated tallow alkyl ammonium. More preferred cationic amphiphilic ions include dicocoalkylammonium and dicyclohexylammonium. In general, the various compounds described above, such as fatty amines, amino alcohol esters, etc., are reacted with acids such as carboxylic acids, inorganic acids, alkyl sulfonic acids or aryl sulfonic acids to make the ammonium ions described above. .
[0022]
  Quaternary ammonium salts can also be used as a source of cationic amphiphilic ions. Examples include, but are not limited to, fatty alkyltrimethylammonium, di (fattyalkyl) dimethylammonium, alkyltrimethylammonium, or 1-alkylpyridinium salts. Here, the counter ion is halogen, methyl sulfate, sulfonate, sulfate or the like. A phosphonium salt such as tetraphenylphosphonium chloride can also be used as a source of amphiphilic ions.
[0023]
  Cationic amphiphilic ions for use in the present invention include R₄N⁺Including those represented by the formula: Where R is independently hydrogen, C₁~ C₃₀Alkyl, C₁~ C₃₀Alkenyl, C₇~ C₃₀Aralkyl, C₇~ C₃₀Alkaryl, 2-ethylhexyl hydrogenated tallow alkyl ammonium, or dimethyl ditallow ammonium.
[0024]
  Another example of a suitable amphiphilic ion is an ammonium ion-containing polymer derived from an amine-containing polymer. Amine-containing polymers are copolymers of dimethylaminoethyl methacrylate or dimethylaminoethyl acrylate, or amine-containing monomers such as vinyl pyridine or vinyl imidazole with other monomers such as methyl acrylate, methyl methacrylate, butyl acrylate, styrene and the like. Good. The polymer may be a terpolymer or tetrapolymer comprising a mixture of amine-containing monomers and two or three other amine-containing polymers, respectively. Such polymers can be prepared by any means, such as radicals (emulsions, suspensions or solutions) or anionic polymerization.
[0025]
  As described above, the amphiphilic counterion may be an anionic amphiphilic counterion. Examples of such anionic amphiphilic ions include, but are not limited to, alkyl benzene sulfonate, alkyl sulfonate, alkyl sulfate, sulfosuccinic acid, sarcosine, alcohol ethoxylate sulfate, alcohol ethoxylate sulfonate, alkyl phosphate, Mention may be made of ions derived from alkyl ethoxylated phosphates, ethoxylated alkyl phenol sulfates, fatty carboxylates, taurates, isethionates, aliphatic carboxylates or polymers having acid groups. Sources of certain preferred examples of anionic amphiphilic ions include, but are not limited to, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, aerosol OT, oleate, ricinoleate, myristate, capron Mention may be made of the acid salts, sodium 2-octyldodecanoate, sodium bis (2-ethylhexyl) sulfosuccinate, sulfonated polystyrene, or homo- or copolymers of acrylic acid or methacrylic acid or their salts.
[0026]
  In general, the above-mentioned amphiphilic counterions and related compounds are commercially available in salt form or can be prepared by one skilled in the art by conventional procedures.
[0027]
  Non-ionic groups include, but are not limited to, hydrophilic groups, hydrophobic groups, alkyl and aryl groups, ethers, polyethers, alkyls, fluorinated alkyls, and the like.
[0028]
  Typically, the diazotizing agent is any metal including, for example, ammonium nitrite, butyl nitrite, dicyclohexylammonium nitrite, ethyl nitrite, isoamyl nitrite, lithium nitrite, sodium nitrite, potassium nitrite, or zinc nitrite or Organic nitrites and can include nitrous acid, nitric oxide, nitrogen dioxide, and mixtures of any of these.
[0029]
  In the first step of the method of the present invention, a reaction batch is prepared by mixing a desired treating agent with a liquid reaction medium. Mixing is preferably performed for a sufficient period of time to substantially dissolve the treating agent. Preferred liquid reaction media can include water, any medium containing water, any medium containing alcohol, and mixtures thereof. Most preferred is a reaction medium based on water. Thereafter, a batch of a diazotizing agent such as sodium nitrite, typically dissolved in the same medium as the treating agent, is added to the treating agent batch and mixed at appropriate conditions sufficient to make a diazonium salt. . Alternatively, both the treating agent and the diazotizing agent can be added simultaneously to the liquid medium and mixed at appropriate conditions. Also preferably, mixing is performed for a sufficient time to substantially dissolve both the treating agent and the diazotizing agent in the liquid medium to form a diazonium salt.
[0030]
  The desired colored pigment is added to the reaction batch in a second step and continuously mixed with the reaction batch for a sufficient amount of time at high shear conditions to produce a reaction product containing the surface modified colored pigment.
[0031]
  The desired colored pigment can be selected from a variety of conventional colored pigments. The colored pigment may be blue, black, brown, cyan, green, purple, magenta, red, yellow and mixtures thereof. Appropriate classifications of colored pigments include, for example, anthraquinone, phthalocyanine blue, phthalocyanine green, diarylide, diazo polymer, monoazo, pyranthrone, perylene, quinophthalone, isoindoline, benzimidazolone, naphthol-AS, β-naphthol, triarylcarboxyl. Mention may be made of nium, diketopyrrolo-pyrrole (DPP), indanthrone, aniline black, quinacridone, and (thio) indigoid. Representative examples of phthalocyanine pigments include copper phthalocyanine blue and green and derivatives thereof (Pigment Blue 15 and Pigment Green 7 and 36). Other examples of phthalocyanine pigments include pigment blue 16 and other metal (aluminum, iron, etc.) phthalocyanine pigments. Representative examples of quinacridone include Pigment Orange 48, Pigment Orange 49, Pigment Red 122, Pigment Red 192, Pigment Red 202, Pigment Red 206, Pigment Red 207, Pigment Red 209, Pigment Violet 19, and Pigment Violet 42. Can be mentioned. Representative examples of anthraquinone include Pigment Red 43, Pigment Red 194 (Perinone Red), Pigment Red 216 (Piantron Red Bromide), Pigment Red 226 (Pyramtron Red), Pigment Yellow 99, Pigment Yellow 123, and Pigment Black 20 can be mentioned. Representative examples of perylene include Pigment Red 123 (Bell Million), Pigment Red 149 (Scarlet), Pigment Red 179 (Maron), Pigment Red 190 (Red), Pigment Violet, Pigment Red 189 (Yellow Shade Red), And CI pigment red 224, CI pigment black 31, and CI pigment black 32. Representative examples of thioindigoid include Pigment Red 86, Pigment Red 87, Pigment Red 88, Pigment Red 181, Pigment Red 198, Pigment Violet 36, and Pigment Violet 38. Representative examples of monoazo, diarylide, and disazo polymers include Pigment Yellow 1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 65, Pigment Yellow 73, and Pigment Yellow 74. Pigment Yellow 83, Pigment Yellow 128, Pigment Yellow 183, Pigment Orange 1, Pigment Orange 6, Pigment Red 220, Pigment Red 242, and Pigment Brown 41. A representative example of a quinophthalone pigment is Pigment Yellow 138. Representative examples of isoindoline are Pigment Yellow 139, Pigment Yellow 185, and Pigment Orange 61. Representative examples of benzoimidazolone pigments are Pigment Yellow 151, Pigment Yellow 180, Pigment Yellow 194, and Pigment Red 208. Representative examples of naphthol-AS pigments include Pigment Red 14, Pigment Red 15, Pigment Red 95, Pigment Red 112, Pigment Red 119, Pigment Red 146, Pigment Red 184, Pigment Red 188, Pigment Red 238, Pigment Red 266. Pigment Orange 22, Pigment Orange 24, and Pigment Violet 13. Representative examples of β-naphthol pigments are Pigment Red 49, Pigment Red 53, and Pigment Orange 17. Representative examples of triarylcarbonium pigments are Pigment Red 81, Pigment Violet 1, Pigment Brown 1, Pigment Blue 1, Pigment Blue 2, and Pigment Blue 10. Representative examples of DPP pigments are Pigment Orange 71, Pigment Orange 73, Pigment Red 254, Pigment Red 255, Pigment Red 264, and Pigment Red 272. Representative examples of indanthrone pigments are Pigment Blue 60 and Pigment Blue 64. A representative example of aniline black is Pigment Black 1. Such pigments are commercially available from a number of suppliers in the form of powders or compressed cakes. This supplier may include BASF, Engelhard, and Sun Chemical. Examples of other suitable colored pigments are given in Color Index, 3rd edition (The Society of Dyer's and Colorists, 1982). Representative examples of black pigments include various carbon blacks (Pigment Black 7) such as Channel Black, Furnace Black, and Lamp Black, which include, for example, Regal®, Black Pearls ( (Registered trademark), Elftex (registered trademark), Monarch (registered trademark), Moguul (registered trademark), and Vulcan (registered trademark), available from Cabot Corporation (for example, Black Pearls (registered trademark) 2000, Black). Pearls (registered trademark) 1400, Black Pearls (registered trademark) 1300, Black Pearls (registered trademark) 1100, Black Pearls (registered trademark) 1000, Black Pearls (registered trademark) 900, Bl ck Pearls (R) 880, Black Pearls (R) 800, Black Pearls (R) 700, Black Pearls (R) L, Elftex (R) 8, Monoarch (R) 1400, Monarch (R) ) 1300, Monarch (R) 1100, Monarch (R) 1000, Monarch (R) 900, Monarch (R) 880, Monarch (R) 800, Monarch (R) 700, Mogul (R) L, Regal (R) 330, Regal (R) 400, Vulcan (R) P). Other suitable carbon blacks include, but are not limited to, Printex 40, Printex 80, Printex 300, Printex L, Printex U, Printex V, Special Black 4, Special Black 5, FW 200e, up to here Raven 780, Raven 890, Raven 1020, Raven 1040, Raven 1255, Raven 1500, Raven 5000, Raven 5250 (previously available from Columbia Chemical) and MA100 and MA4 ). The width of the BET surface area of colored pigments is typically large, which is measured by nitrogen adsorption. The surface area of the colored pigment is preferably 85 m²/ G or larger, more preferably 100 m²/ G or greater, which corresponds to a relatively small primary / aggregate particle size. Such a surface area has been found to provide a relatively uniform dispersion and an effective concentration of treatment agent on the pigment surface, and a relatively high yield of surface modified colored pigments after post-treatment techniques. ing. If the preferred relatively large surface area of the colored pigment (and therefore the corresponding relatively small particle size) is not readily obtained, the pigment is subjected to conventional refinement or particle size reduction techniques such as ball milling or jet milling to provide the pigment. It is known to those skilled in the art to reduce the particle size of to a desired particle size.
[0032]
  As described above, in the second step, the desired colored pigment is added to the reaction batch and mixed with the reaction batch for a sufficient amount of time at high shear conditions to produce a reaction product comprising the surface modified colored pigment. A preferred embodiment utilizes an apparatus that can react in a suitable vessel at high shear conditions and provide continuous particle size reduction for mixing. This includes, for example, horizontal media mill, vertical media mill such as attritor, ball mill, hammer mill, pin disc mill, fluid energy mill, jet mill, fluid jet mill, impact jet mill, funnel stator, pelletizer, homogenizer It may be a device capable of providing grinding, impact or simple impact action such as a pulverizer, sonic grinder, cavitation device or the like. In the present invention, “high shear” means that the particle size distribution of the colored pigment is reduced to a desired size, and a new surface of the colored pigment is continuously exposed to the reaction batch, thereby binding to the surface of the colored pigment. It means energy sufficient to give the distribution and concentration of the treating agent and to improve the overall yield of the product. Preferably, the high shear mixing step is performed using the same vessel as that used to prepare the reaction batch of the treating agent and diazotizing agent. More preferably, the container is equipped with suitable means for applying heat, such as a heating cover, a thermocouple, and the like.
[0033]
  Typically, high shear mixing is performed at a temperature of about 0 ° C. to 90 ° C. for 30 minutes to 48 hours. Preferably, the high shear mixing is performed at a temperature of about 50 ° C to 75 ° C for 1 hour to 24 hours. This is because such a range has been found to provide surface modified colored pigments with improved dispersibility, stability and color strength. In the most preferred embodiment, one or more additional or stepwise additions of treatment agent and diazotization agent are made to the vessel to obtain maximum reaction efficiency and to uniformly treat the treatment agent on the surface of the colored pigment. I do. In other words, instead of adding all at the same time, a given amount (calculated to achieve the desired level of binding of the treating agent) and diazotizing agent is added twice or more times. Separately introduce into containers. The total amount of treating agent added for the surface modification of the colored pigment achieves the colloidal stability of the surface modified colored pigment in the particular composition and also the specific properties of the desired end product application, For example, an amount sufficient to improve water fastness. Diazotization is possible when low levels of processing agents are desiredNokiIs typically about 0.01-5.0 μmol / nitrogen surface area (m²). Diazotization is possible when conventional levels of processing agents are desiredNokiIs typically about 5.0 to 50.0 μmol / nitrogen surface area of the colored pigment (m²), In a quantity (ie present in the reaction batch). Finally, those skilled in the art will recognize that the pH of the reaction mixture may vary depending on the particular processing agent and the most efficient reaction conditions, and this may be, for example, an acidic or neutral pH.
[0034]
  The surface modified colored pigment dispersion prepared by the method of the present invention is further purified or classified to remove impurities and other undesirable free species that may be present together in the dispersion as a result of the manufacturing process. be able to. In a preferred embodiment, the surface modified colored pigment dispersion prepared by the method of the present invention is subjected to a classification step such as centrifugation to provide particles having a size greater than about 1.0 μm, preferably about 0. Particles larger than 5 μm are substantially removed. In addition, the dispersion is preferably purified to remove any undesired free species such as unreacted processing agents, reaction by-products or feed impurities. The dispersion can be purified using known techniques of ultrafiltration / osmotic filtration using membranes or ion exchange to remove substantial amounts of free ions and unwanted species. Alternatively, the dispersion can be purified using an acid wash, dialysis or concentration (dehydration) step. Also preferably, optional counter-ion exchange can be performed, whereby the counter-ions constituting part of the surface-modified colored pigment can be exchanged or replaced with other counter-ions. This utilizes known ion exchange techniques such as ultrafiltration, reverse osmosis, ion exchange columns and the like. Examples of specific counterions that can be exchanged include, but are not limited to, Na⁺, K⁺, Li⁺, NH₄ ⁺, Ca²⁺, Mg²⁺, Cl⁻, NO₃ ⁻, NO₂ ⁻, Acetate, carboxylate, and Br⁻Can be mentioned. Such additional classification and purification methods are relatively fully disclosed in US patent application Ser. No. 09 / 240,291, filed Jan. 29, 1999. The description of this patent specification is hereby incorporated by reference in its entirety.
[0035]
  Surface-modified colored pigments prepared by the method of the present invention can be used in water or solvent based compositions containing conventional pigments. The following discussion regarding the ink composition is equally applicable to other liquid systems for coatings, paper, inks, toners, adhesives, latexes, fabrics and fibers.
[0036]
  Ink compositions containing surface-modified colored pigments prepared by the method of the present invention have been found suitable for use in imaging applications, particularly inkjet ink applications. Such inks and inkjet compositions exhibit improved formulation and storage stability. In addition, images produced with such inks and inkjet compositions exhibit good waterfastness and color strength.
[0037]
  Surface modified colored pigments prepared by the method of the present invention are based on water or solvent in an amount effective to provide the desired image quality, eg, optical density, without adversely affecting the ink performance. Present in the ink or inkjet ink composition. The surface-modified colored pigment is typically present in an amount of about 1% to about 20%, preferably about 2% to about 10%, based on the weight of the ink composition. In addition, surface-modified colored pigments are typically possible to enable a stable colloidal suspension of the pigment in the liquid vehicle and to prevent blockage of the ink channels and nozzles when used in the desired printing application. As few as possible. For example, the preferred average particle size of the surface-modified colored pigment for use in a thermal ink jet printer is generally less than 1.0 μm, preferably in the range of about 0.005 μm to about 0.3 μm.
[0038]
  The ink compositions of the present invention can be made by conventional techniques recognized by those skilled in the art, for example by combining or mixing the desired components in a suitable water or solvent based medium. If the ink and inkjet composition is a water based system, a significant amount of water is typically used, preferably distilled or deionized water. For example, the amount of water or similar medium is typically about 50% to about 95%, preferably about 60% to about 80%, based on the weight of the ink or inkjet composition.
[0039]
  The inks and ink jet compositions of the present invention can be prepared at the desired pH by adding a suitable base such as sodium hydroxide, ammonium hydroxide, triethylamine, dimethylethanolamine, or the like, or a suitable acid such as inorganic acid, hydrochloric acid, sulfuric acid, or the like. Can be buffered. In addition, soluble polymers can be added to the ink composition to improve the waterfastness of the image provided by the ink composition. Examples of these polymers include polyvinyl alcohol, polyester, polyester melamine, styrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-maleic acid-alkyl acrylate copolymer, styrene-methacrylic acid copolymer, and styrene-methacrylic acid-alkyl acrylate copolymer. Styrene-maleic acid half ester copolymers, vinyl naphthalene-acrylic acid copolymers, vinyl naphthalene-maleic acid copolymers, and salts thereof. Further polymers include polyvinyl imidazole, polyvinyl imidazole derivatives, copolymers of vinyl imidazoles, copolymers of vinyl imidazole derivatives, polyvinyl pyridines, polyvinyl pyridine derivatives, vinyl pyridines as listed in PCT International Publication WO 96/18688. And copolymers of vinyl pyridine derivatives, polyethyleneimine, polyethyleneimine derivatives, and mixtures thereof. The description of this specification is herewith referred to, and is hereby incorporated in its entirety.
[0040]
  Suitable additives can also be added to the ink or inkjet composition to provide some desired properties while maintaining the stability of the composition. For example, surfactants or suitable polymers can be used to further improve the colloidal stability of the colored pigments in the ink composition. Other additives are also known in the art, examples include wetting agents, biocides, binders, drying accelerators, penetrants and the like. Examples of wetting agents include ethylene glycol, propylene glycol, diethylene glycol, glycerin, dipropylene glycol, polyethylene glycol, polypropylene glycol, alkanediol, amide, ether, carboxylic acid, ester, alcohol, organic sulfide, organic sulfoxide, sulfone, Mention may be made of alcohol derivatives, 2-pyrrolidone, ether derivatives, amino alcohols and ketones. The amount of a particular additive depends on various factors, but is generally present in an amount of 0% to 40%, preferably 0.1% to 10%. However, the amount may be outside this range.
[0041]
  A printed image can be made from an ink or inkjet composition of the present invention by creating an image on a substrate using the ink or inkjet composition of the present invention in a suitable printing device. Suitable ink jet printers include thermal printers, piezoelectric printers, continuous printers, valve printers, and the like. Similarly, any substrate can be used. Examples of the substrate include flat paper, bond paper, coated paper, transparent material, woven material, plastic, polymer film, inorganic substrate, and the like.
[0042]
  Surface-modified colored pigments prepared by the method of the present invention as described above may be other water or solvent based systems such as, but not limited to, coatings, paints, paper, adhesives, latexes, toners, textiles and Can be used on fiber. For example, systems based on water or solvents can be prepared by combining or mixing surface-modified colored pigments with suitable resins such as alkyd resins, acrylic resins, polyester resins, silicate resins, urethane resins, epoxy resins and the like.
[0043]
  In the following, the present invention is illustrated by non-limiting examples.
[0044]
  Example 1: Preparation of surface modified colored pigment
  A 650 g ceramic grinding media with an average diameter of 2 mm (available from CB Mill, Gurney, Illinois, USA) and 260 ml of deionized water, available from Union Process, Akron, Ohio, USA. ). The attritor was heated to 60 ° C. and operated at a speed of 440 rpm. Sulfanilic acid (6.76 g) (available from Aldrich Chemical, Milwaukee, Wis.) Was added to the attritor and ground with ceramic media for about 30 minutes until substantially all of the sulfanilic acid was dissolved. A batch containing 2.73 g of sodium nitrite (available from Aldrich Chemical, Milwaukee, Wis.) Dissolved in 20.0 g of deionized water was then added to the grinder. Immediately after adding the sodium nitrite batch, the surface area is 130m²/ G of 30 g copper phthalocyanine blue (Pigment Blue, Sunfast 15: 4, Dye Index (CI) No. 74160, available from Sun Chemical, Cincinnati, Ohio) was added to the grinder. The resulting mixture was mixed for about 1 hour, after which 6.76 g of additional sulfanilic acid was added, and 2.73 g of additional sodium nitrite was added. The mixture was allowed to react at 60 ° C. for about 5 hours with an attritor speed of 440 rpm. The product obtained is C₆H₄SO₃ ⁻Na⁺It was a surface-modified blue pigment dispersible in water having a group. The product was worked up. This post-treatment was performed by filtering the product through a 20 μm screen and using a Pall SLP1053 module filtration system (available from Pall Filtron, Northborough, Mass.) To the filtered product. Further ultrafiltration (generally referred to as membrane filtration) until the product is colorless. The surface modified blue pigment dispersion was then centrifuged to substantially remove all pigment particles having a particle size greater than 0.35 μm. The overall yield of the dispersion after centrifugation was 60 wt% based on the blue pigment.
[0045]
  Sulfur and nitrogen were measured by a combustion technique using Fission's EA-1108 gas chromatograph as an indicator of the amount or concentration of treatment agent chemically bound to the surface of the colored pigment. In addition, the particle size distribution was measured using a MICROTRAC ™ ultrafine particle analyzer (available from Honeywell, Minneapolis, Minn., USA). The following conditions were used here: opaque, non-spherical particles, particle density 18.6 g / m³Water as dispersion, test time 6 minutes. For comparison, the sulfur content, nitrogen content, and particle size distribution were determined for untreated SunfastBlue 15: 4 pigment.
[0046]
  Table 1 shows the sulfur content, nitrogen content, and particle size distribution of the surface-modified blue pigment and the untreated blue pigment produced by the method of the present invention.
[Table 1]

* Ratio of the amount of sulfanilic acid added to the pigment (wt%)
** Sulfur content obtained (wt%) after membrane filtration and centrifugation
*** Nitrogen content obtained (wt%) after membrane filtration and centrifugation
*** Particle size distribution was determined based on wt% or vol% immediately after treatment and prior to membrane filtration and centrifugation. The particle size of the untreated SunfastBlue 15: 4 pigment was determined with a 0.1 wt% aqueous dispersion of pigment with 0.7 wt% Tween 80 dispersant (available from Aldrich Chemical, Milwaukee, Wis.).
[0047]
  As shown in Table 1, adding the sulfanilic acid with sodium nitrite using the method of the present invention, as shown by the increase in sulfur content,₆H₄SO₃ ⁻Na⁺This results in the production of surface modified blue pigments having groups. The ability to achieve an average particle size of less than 0.5 μm and a maximum particle size of less than 1.0 μm is also related to a relatively uniform and efficient processing method. Furthermore, the yield of surface modified colored pigments after ultrafiltration and centrifugation is significantly improved by using the method of the present invention.
[0048]
  The surface-modified blue pigment prepared by the method of the present invention can be easily dispersed in an aqueous medium and exhibits good color hue and color intensity. On the other hand, untreated pigments are very difficult to disperse in water, and when left untreated for a short time, they are hardened, that is, aggregate.
[0049]
  Example 2: Preparation of surface modified colored pigment
  A surface modified phthalocyanine blue pigment was prepared by repeating the method of Example 1. However, here, the amount of the first addition of sulfanilic acid (before the introduction of the pigment) is 3.16 g, the amount of the second addition (after the introduction of the pigment) is 3.16 g, and the first addition of sodium nitrite The amount of addition (before pigment introduction) was 1.26 g, and the amount of the second addition (after pigment introduction) was 1.26 g. Furthermore, the colored pigment has a surface area of 60 m.²/ G phthalocyanine blue (Pigment Blue, Zulu 4960, Color Index (CI) No. 47160, available from Engelhard, Beachwood, Ohio). The product obtained is C₆H₄SO₃ ⁻Na⁺It was a surface-modified blue pigment having a group. The product was filtered through a 20 μm screen and ultrafiltered as shown in Example 1. The surface modified blue pigment dispersion was centrifuged to substantially remove all pigment particles having a particle size greater than 0.35 μm. The overall yield of the dispersion after centrifugation was 13 wt% based on the blue pigment.
[0050]
  The particle size distribution of the surface-modified colored pigment is as shown in Table 2.
[Table 2]

*** Particle size distribution was determined immediately after treatment using the conditions shown in Example 1.
[0051]
  Similar to Example 1, the surface-modified blue pigment prepared by the method of the present invention was easily dispersed in an aqueous medium and showed good color and color strength. However, to improve the yield of surface modified colored pigments after post-treatments such as ultrafiltration and centrifugation, it is possible to use pigments with a relatively large surface area (as shown in Example 1) or colored pigments. It is recognized that the particle size can be reduced prior to or during the introduction of a conventional particle size reduction treatment into the reaction batch containing the treating agent and diazotizing agent.
[0052]
  Example 3: Preparation of surface modified colored pigment
  A surface modified phthalocyanine blue pigment was prepared by repeating the method of Example 1. However, here, the amount of the first addition of sulfanilic acid (before the introduction of the pigment) is 2.71 g, the amount of the second addition (after the introduction of the pigment) is 2.71 g, and the first addition of sodium nitrite The amount of addition (before pigment introduction) was 1.08 g, and the amount of the second addition (after pigment introduction) was 1.08 g. The product obtained is C₆H₄SO₃ ⁻Na⁺It was a surface-modified blue pigment having a group. The product was filtered through a 20 μm screen and ultrafiltered as shown in Example 1. The surface modified blue pigment dispersion was centrifuged to substantially remove all pigment particles having a particle size greater than 0.35 μm. The overall yield of the dispersion after centrifugation was 40 wt% based on the blue pigment.
[0053]
  The particle size distribution of the surface-modified colored pigment is as shown in Table 3.
[Table 3]

*** Particle size distribution was determined immediately after treatment using the conditions shown in Example 1.
[0054]
  Similar to Example 1, the surface-modified blue pigment prepared by the method of the present invention was easily dispersed in an aqueous medium and showed good color and color strength. However, to improve the yield of surface-modified colored pigments after post-treatments such as ultrafiltration and centrifugation, increasing the amount of treating agent and diazotizing agent (first or second introduction) As an additional step-by-step introduction).
[0055]
  Example 4: Preparation of surface modified colored pigment
  A surface modified phthalocyanine blue pigment was prepared by repeating the method of Example 1. Here, however, instead of sulfanilic acid, p-amino-benzoic acid (available from Aldrich Chemical, Milwaukee, Wis.) Is added as a treating agent at the initial addition of 5.34 g, and the second addition is 5. 34 g was added. The product obtained is C₆H₄CO₂ ⁻Na⁺It was a surface-modified blue pigment having a group. The product was filtered through a 20 μm screen and ultrafiltered as shown in Example 1. The surface modified blue pigment dispersion was centrifuged to substantially remove all pigment particles having a particle size greater than 0.35 μm. The overall yield of the dispersion after centrifugation was 20 wt% based on the blue pigment.
[0056]
  The particle size distribution of the surface-modified colored pigment is as shown in Table 4.
[Table 4]

*** Particle size distribution was determined immediately after treatment using the conditions shown in Example 1.
[0057]
  Similar to Example 1, the surface-modified blue pigment prepared by the method of the present invention was easily dispersed in an aqueous medium and showed good color and color strength. However, to improve the yield of surface-modified colored pigments after post-treatments such as ultrafiltration and centrifugation, pigments with a relatively large surface area can be used, or colored pigments can be subjected to conventional particle size reduction treatments. Thus, it is recognized that the particle size can be reduced before introduction into the reaction batch containing the treating agent and diazotizing agent. Furthermore, an increase in the amount of treating agent and diazotizing agent (as a first or second addition or as an additional stepwise addition) may be preferred.
[0058]
  Example 5: Preparation of surface modified colored pigment
  A 650 g ceramic grinding media with an average diameter of 2 mm (available from CB Mill, Gurney, Illinois, USA) and 260 ml of deionized water, available from Union Process, Akron, Ohio, USA. ). The attritor was heated to 60 ° C. and operated at a speed of 440 rpm. Sulfanilic acid (2.90 g) (available from Aldrich Chemical, Milwaukee, Wis., USA) was added to the attritor and ground with ceramic media for approximately 30 minutes until substantially all of the sulfanilic acid was dissolved. A batch containing 1.16 g sodium nitrite (available from Aldrich Chemical, Milwaukee, Wis.) Dissolved in 20.0 g deionized water was then added to the grinder. Immediately after adding to the sodium nitrite batch, the surface area is 60m²/ G of 30 g magenta 122 pigment (Sunfast 122, Dye Index (CI) No. 73915, available from Sun Chemical, Cincinnati, Ohio) was added to the grinder. The resulting mixture was allowed to mix for about 1 hour, after which 2.2 g of additional sulfanilic acid was added, and 0.87 g of additional sodium nitrite was added. The mixture was allowed to react at 60 ° C. for about 1 hour with an attritor speed of 440 rpm, after which 2.2 g of additional sulfanilic acid and 0.87 g of sodium nitrite were added. The mixture was allowed to react at 60 ° C. for about 5 hours with an attritor speed of 440 rpm. The product obtained is C₆H₄SO₃ ⁻Na⁺It was a surface-modified magenta pigment having a group. The product was filtered through a 20 μm screen and ultrafiltered as shown in Example 1. The surface modified magenta pigment dispersion was centrifuged to substantially remove all pigment particles having a particle size greater than 0.35 μm. The overall yield of the dispersion after centrifugation was 35 wt% based on magenta pigment.
[0059]
  The particle size distribution of the surface-modified colored pigment is as shown in Table 5.
[Table 5]

*** Particle size distribution was determined immediately after treatment using the conditions shown in Example 1.
[0060]
  Similar to Example 1, the surface modified magenta pigment prepared by the method of the present invention was readily dispersed in an aqueous medium and exhibited good color and color strength. However, to improve the yield of surface modified colored pigments after post-treatments such as ultrafiltration and centrifugation, it is possible to use pigments with a relatively large surface area (as in Example 1) or colored pigments. It is recognized that the conventional particle size reduction treatment can be performed to reduce the particle size before introduction into the reaction batch of the treatment agent and diazotizing agent.
[0061]
  Comparative Example 6: Preparation of surface-modified colored pigment
  A 650 g ceramic grinding media with an average diameter of 2 mm (available from CB Mill, Gourney, Illinois, USA) and 260 ml of deionized water, available from Union Process, Akron, Ohio, USA. ). The attritor was heated to 60 ° C. and operated at a speed of 440 rpm. Unlike Example 1 where the batch of treating agent and diazotizing agent was first introduced into the attritor, the surface area was 130 m.²/ G of 30 g copper phthalocyanine blue (Pigment Blue, Sunfast 15: 4, Dye Index (CI) No. 74160, available from Sun Chemical, Cincinnati, Ohio) to the grinder and 6.76 g sulfanilic acid added It was. The pigment / sulfanilic acid mixture was ground with ceramic media for about 30 minutes until all the sulfanilic acid was substantially dissolved. A batch consisting of 2.73 g of sodium nitrite (available from Aldrich Chemical, Milwaukee, Wis.) Dissolved in 20.0 g of deionized water was then added to the grinder. The resulting mixture was allowed to react for about 1 hour after which 6.76 g of additional sulfanilic acid was added and 2.73 g of additional sodium nitrite was added. As in Example 1, the mixture was reacted at 60 ° C. for about 5 hours with an attritor speed of 440 rpm, but 6.67 g of additional sulfanilic acid and 2.73 g of sodium nitrite were added. The mixture was further reacted overnight. The product obtained is C₆H₄SO₃ ⁻Na⁺It was a surface-modified blue pigment having a group. The product was filtered through a 20 μm screen and ultrafiltered as shown in Example 1. The surface modified blue pigment dispersion was centrifuged to substantially remove all pigment particles having a particle size greater than 0.35 μm. The overall yield of the dispersion after centrifugation was only 35 wt% based on the blue pigment. In contrast, the yield when using the method of the present invention is 60%.
[0062]
  The particle size distribution of the surface-modified colored pigment is as shown in Table 6.
[Table 6]

*** Particle size distribution was determined immediately after treatment using the conditions shown in Example 1.
[0063]
  Compared with Example 1, Table 6 shows the particle size distribution of the surface-modified colored pigment. Compared to the inventive method shown in Example 1, the conventional method used in Example 6 is not as efficient (especially 95%) as shown by the relatively large particle size distribution and after workup The yield of surface modified colored pigments at is significantly lower.
[0064]
  Comparative Example 7: Preparation of surface-modified colored pigment
  100 g of deionized water was added to a 600 ml glass beaker on a hot plate equipped with a mechanical stirrer. Water was heated to 60 ° C. and stirred at 450 rpm. Sulfanilic acid (2.1 g) (available from Aldrich Chemical, Milwaukee, Wis.) Was added to the beaker and stirred for about 30 minutes until substantially all of the sulfanilic acid was dissolved. A batch consisting of 0.83 g sodium nitrite (available from Aldrich Chemical, Milwaukee, Wis.) Dissolved in 10.0 g deionized water was then added to the beaker. Immediately after adding the sodium nitrite batch, the surface area is 60m²/ G of 5.0 g phthalocyanine blue (Pigment Blue, Zulu 4960, Dye Index (CI) No. 74160, available from Engelhard, Inc., Beachwood, Ohio) was added to the beaker. The resulting mixture was reacted at 60 ° C. for about 6 hours at an agitator speed of 450 rpm. The product obtained is C₆H₄SO₃ ⁻Na⁺It was a surface-modified blue pigment having a group. The product was filtered through a 20 μm screen and ultrafiltered as shown in Example 1. The surface modified blue pigment dispersion was centrifuged to substantially remove all pigment particles having a particle size greater than 0.35 μm. The overall yield of the dispersion after centrifugation was less than 10 wt% based on the blue pigment.
[0065]
  The particle size distribution of the surface-modified colored pigment is as shown in Table 7.
[Table 7]

*** Particle size distribution was determined immediately after treatment using the conditions shown in Example 1.
[0066]
  The particle size distribution of the surface-modified colored pigment is as shown in Table 7. Compared to the inventive method shown in Example 1, the conventional method used in Example 7 is not as efficient (especially 95%) as shown by the relatively large particle size distribution and after workup The yield of surface modified colored pigments at is significantly lower. The surface modified colored pigment also created a substantial layer of pasty material that had to be discarded from the 20 μm screen. The product was not suitable for combination with an aqueous medium.
[0067]
  Example 8: Dispersion stability test of surface-modified colored pigment
  The surface modified colored pigment of Example 1 (after centrifugation) was concentrated by ultrafiltration to a solids content of 4.1%. 10 ml of the concentrated dispersion was placed in a 20 ml glass bottle. The bottle was capped and placed in a furnace (available from VWR Scientific Products, Willard, Ohio) and heated to 70 ° C. for 7 days. Table 8 shows the particle size distribution of the surface-modified colored pigment both before (Example 8A) and after (Example 8B) the treatment (aging) by the furnace. As shown in Table 8, the surface modified blue pigment made by the process of the present invention at a concentration of 4.1% showed a high level of colloidal stability even after treatment with this furnace.
[Table 8]

****** Particle size distribution was determined after the post-treatment steps of ultrafiltration and centrifugation.
[0068]
  Example 9: Preparation of ink
  The surface modified colored pigment of Example 1 (after centrifugation) was added to distilled water to make an aqueous dispersion with 8.5 wt% pigment. The dispersion was an inkjet ink containing 3 wt% surface modified Sunfast 15: 4 blue pigment, 7.5 wt% ethylene glycol, 7.5 wt% glycerol, and 4.0 wt% isopropanol, and the balance distilled water. .
[0069]
  The resulting ink was used to print blue on a series of standard paper (Xerox 4024, Fox Bond, KG) and one transparent substrate with a Canon Bubblejet 4200 printer equipped with a BCI-21 cartridge. The results for tristimulus values, water fastness (WF), and optical density (OD) are shown in Table 9. For comparison, Table 9 also shows the results obtained with the factory-supplied BCI-21 cartridge blue dye. For further comparison, the same tests were performed on pigments based on ENCAD GO Graphic Outdoor Ink (available from ENCAD, San Diego, Calif.) And the results are shown in Table 9.
[0070]
  Using a Hunter Lab Scan II device (available from Hunter Associates Laboratory, Reston, VA, USA)^*, A^*And b^*It was determined. Optical density (OD) was determined according to ANSI method CGATS, 4-1993, using a Macbeth densitometer RD915S (available from GretagMacBeth LLC, New Windsor, NY). For water fastness (WF), the printed material is first hung at an angle of about 45 °, 25 ml of water is spouted for a predetermined period (1 minute after printing, 5 minutes after printing, etc.), and the color movement is observed. Decided by. Here, it is considered that the printing is water resistant when the sprayed water flows transparently.
[0071]
  Compared to the two commercially available inks described above, the results in Table 9 show that the surface modified blue pigment prepared by the method of the present invention is an unoptimized inkjet ink composition and is It shows that the paper has good printing ability and water fastness.
[Table 9]

[0072]
  Surface-modified colored pigments prepared by the method of the present invention exhibit good printing performance, even in non-optimized compositions, and as an alternative to commercially available dye and pigment colored products Attractive. The resulting inkjet ink provides an aesthetically pleasing blue print, as indicated by tristimulus values and waterfastness.
[0073]
  As mentioned above, the surface-modified colored pigments prepared by the method of the present invention are useful in a wide range of applications based on water or solvent, particularly in ink compositions that provide the desired color and intensity. Unlike conventional pigments, the surface modified colored pigments according to the present invention can be easily dispersed in a desired liquid vehicle. Furthermore, the surface-modified colored pigments according to the invention are stable as colloids in the liquid vehicle and do not require conventional grinding or the aid of a dispersant. The surface modified colored pigments according to the present invention require only low shear mixing or agitation in order to disperse in the liquid vehicle.
[0074]
  The above description of the invention is illustrative only and is not intended to limit the invention. Accordingly, those skilled in the art can make changes or modifications with reference to the above-described techniques or by implementing the present invention. The embodiments of the present invention have been chosen and described in order to explain the principles of the present invention, and accordingly, those skilled in the art will be able to make various modifications to the various aspects of the present invention, as appropriate to the particular application intended. Embodiments can be used. The scope of the invention is defined by the claims and their equivalents.

Claims (41)

(A) preparing a reaction mixture containing a treating agent having at least one diazotizable group and a diazotizing agent in a liquid medium;
(B) adding a colored pigment to the reaction mixture; and (c) mixing the colored pigment and the reaction mixture under high shear mixing conditions to produce a reaction product comprising a surface-modified colored pigment;
Only it contains, and the diazotizable group is a nitrogen-containing group to produce a diazonium group by reaction with diazotizing agent, surface modification process for the preparation of colored pigments.   The method of claim 1, wherein the reaction mixture is prepared by mixing the treating agent and the diazotizing agent under high shear mixing conditions to form a diazonium salt.   The method of claim 2, wherein the reaction mixture is mixed by using an apparatus that provides a grinding action.   The method according to claim 2, wherein the reaction mixture is mixed by using an apparatus that provides an impact action.   The method of claim 2, wherein the reaction mixture is mixed by using an apparatus that provides for particle size reduction.   The method of claim 2, wherein the mixing is performed by a horizontal or vertical media mill.   The method of claim 6, wherein the media mill is a grinder.   The method of claim 6, wherein the media mill has grinding media.   The method of claim 8, wherein the grinding media is ceramic.   The method of claim 1, wherein the mixing of step (c) is performed by using an apparatus that provides a grinding action.   The method of claim 1, wherein the mixing of step (c) is performed by using an apparatus that provides an impact action.   The method of claim 1, wherein the mixing of step (c) is performed by using an apparatus that provides for reducing the particle size.   The method of claim 1, wherein the mixing of step (c) is performed by a horizontal or vertical media mill.   The method of claim 13, wherein the media mill is a grinder.   The method of claim 14, wherein the media mill comprises attrition media.   The method of claim 15, wherein the grinding media is ceramic.   The method of claim 1, further comprising adding the treating agent at least once more in step (c).   The method of claim 1, further comprising adding a diazotizing agent at least once more in step (c).   The method of claim 1, further comprising adding the treating agent and diazotizing agent at least once again in step (c).   The method according to claim 1, wherein a treatment for reducing the size of the colored pigment is first performed before the step (b).   The method of claim 1, wherein the diazotizable group is attached to the surface of the colored pigment in an amount sufficient to improve the dispersibility of the surface-modified colored pigment in a liquid medium.   The method according to claim 1, wherein the mixing in step (c) is performed at a temperature of 0C to 90C for 30 minutes to 48 hours.   The method according to claim 22, wherein the mixing in step (c) is performed at a temperature of 50C to 75C for 1 hour to 24 hours. (D) purifying or classifying the surface-modified colored pigment;
The method of claim 1, further comprising:   The method of claim 1, further comprising: (d) exchanging a portion of a counterion that is part of the surface modified colored pigment with at least one different counterion. (D) purifying or classifying the surface-modified colored pigment; and (e) exchanging a part of the surface-modified colored pigment with at least one different counter ion;
The method of claim 1, further comprising:   The method according to claim 24, wherein the purification or classification step of the step (d) is performed by ultrafiltration or ion exchange.   The method according to claim 24, wherein the purification or classification step of step (d) is performed by centrifugation.   26. The method of claim 25, wherein the exchange of step (d) is performed by ion exchange.   A composition comprising a surface-modified colored pigment made by the method of claim 1 and an aqueous liquid vehicle.   32. The composition of claim 30, wherein the composition is an inkjet ink composition. (A) preparing a reaction mixture containing a treating agent having at least one diazotizable group and a diazotizing agent in a liquid medium;
(B) adding a colored pigment to the reaction mixture;
(C) mixing the colored pigment and the reaction mixture under high shear mixing conditions to produce a reaction product comprising a surface-modified colored pigment;
(D) purifying or classifying the surface-modified colored pigment; and (e) adding the purified or classified surface-modified colored pigment to a liquid vehicle to produce an ink composition;
Only it contains, and the diazotizable group is a nitrogen-containing group to produce a diazonium group by reaction with diazotizing agent, process for the preparation of the ink composition.   33. The method of claim 32, further comprising exchanging a portion of the surface modified colored pigment with at least one different counter ion before or after step (d).   35. The method of claim 32, wherein the liquid vehicle is aqueous.   The method of claim 32, wherein the ink composition is an inkjet ink.   The method according to claim 1, wherein the treatment agent contains sulfanilic acid.   The method according to claim 1, wherein the treatment agent contains p-aminobenzoic acid. The method according to claim 1, wherein the treatment agent has at least one aromatic group, and the surface-modified pigment has an aromatic group directly bonded to the surface of the colored pigment.   The method according to claim 32, wherein the treatment agent contains sulfanilic acid.   The method according to claim 32, wherein the treatment agent contains p-aminobenzoic acid. The method according to claim 32, wherein the treatment agent has at least one aromatic group, and the surface-modified pigment has an aromatic group directly bonded to the surface of the colored pigment.